This invention relates generally to a gas adsorption and desorption method using an adsorbent. More specifically, the present invention is directed to a method of treating a gas mixture for separating respective components thereof by adsorption and to a method of desorbing a gas adsorbed on a non-carbonaceous adsorbent.
Treatment of a gas mixture with an adsorbent such as activated carbon, silica gel, alumina or zeolite for separation of respective components thereof is now widely carried out in various fields. A packed bed, moving bed or fluidized bed system is generally employed for such a treatment.
In order to effectively perform adsorption and desorption, it is important to select a suitable adsorbent and to use suitable temperature and pressure. In particular, the selection of a suitable adsorbent is essential especially when the gas to be treated contains two or more components to be separated from each other. When there is available an adsorbent having a high selectivity to one of the components of the gas to be treated, such an adsorbent is generally used even if the adsorption power thereof is not fully satisfactory. For example, when a gas containing a chlorofluorocarbon and moisture is to be treated, activated carbon is used notwithstanding the fact that the chlorofluorocarbon is more adsorptive to zeolite than to activated carbon, because of the strong adsorbing power of the zeolite to moisture.
Relative adsorbability of two gaseous components contained in a gas to be treated can be changed to some extent by varying temperature and pressure at which the adsorption of the gas is performed. However, it is practically very difficult to control the selectivity by temperature and pressure.
Thus, in the conventional adsorption method, it is very difficult to effectively treat a mixed gas containing two or more components using an adsorbent which can adsorb at least two of the components. Similarly, in desorption, it is difficult to selectively desorb one of a plurality of the adsorbed gas components from the adsorbent by control of the temperature and pressure.